Final answer:
Pregnancy symptoms start a few weeks after conception, with early signs including morning sickness and increased sensitivity to odors caused by increased levels of pregnancy-related hormones. These symptoms may subside as the placenta takes over hormone production. Other subsequent symptoms include heartburn, frequent urination, and skin changes.
Step-by-step explanation:
Pregnancy symptoms typically begin a few weeks after conception. The most common early signs include nausea often referred to as 'morning sickness', which can actually occur throughout the day, and increased sensitivity to odors which can also trigger vomiting. These symptoms are caused by an increase in various pregnancy-related hormones, such as estrogen, progesterone, and hCG (human chorionic gonadotropin).
From weeks 7 to 12, these hormones are primarily generated by the corpus luteum, an endocrine structure that forms in the ovaries following ovulation. Over time, the placenta starts to take over as the primary endocrine organ of pregnancy, and it is around this time that nausea typically begins to subside. However, other symptoms like heartburn, frequent urination, and skin changes including stretch marks and increased melanin production may start appearing due to the ever-increasing levels of these hormones and the physical changes taking place in the body.
Apart from these, weight gain primarily occurs in the breasts and the abdominal region due to the growing fetus and the associated physiological changes taking place in the female body.
Learn more about Pregnancy Symptoms